


Syreni

by Shimegami



Category: Free!
Genre: Alternate Universe - Merpeople, Everyone shows up eventually, I Blame Tumblr, I Don't Even Know, M/M, Marine Biology AU, Merpeople, Merpeople Culture
Language: English
Status: In-Progress
Published: 2013-12-09
Updated: 2014-10-20
Packaged: 2018-01-04 04:28:27
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 13,375
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1076537
Author URL: https://archiveofourown.org/users/Shimegami/pseuds/Shimegami
Summary: <blockquote class="userstuff">
              <p>In the early twentieth century, mermaids were discovered and documented by science.  A hundred years later, Rei and Nagisa continue to expand mermaid science by studying a certain individual they’ve named ‘Haru’.</p>
<p>Inspired by Tumblr user niuniente's Marine Biology AU.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Hello! If you follow me on tumblr, you'll know that I've been working on this fic for a while (and having existential crisises about my others). Since I got another chapter of Half A Metter out, I'm now going to post this one here too. :>
> 
> This is the mer!Haru and mer!Mako marine biology AU that no one wanted me to write but I'm doing it anyways. Inspired by the lovely niuniente on tumblr's artwork and her lovely pictures for this universe.

The October breeze bites at Rei’s ears as he steps out of the ship’s cabin. Winters in Iwatobi Bay may be mild, but the fall air still has a bit of a bite, especially on the open sea.

It’s also a sign that their observation period will soon end, so Rei’s got to make the most of it before it does.

Picking up his binoculars, Rei uses them to scan the rocky outcrops to look for a figure they’ve become very acquainted with for the past two years. After a moment, he catches a glimpse of silver-gray tail draped over a algae-encrusted rock, attached to a slim, muscled torso and a head of black hair that’s currently pillowed on two strong arms, napping as if the chill air was a warm spring day.

Rei finds a smile quirking his lips. Seriously, some things never changed.

“Rei-chaaaaan! Don’t start observing without me!!”

The smile morphs into a wince. Indeed, some things didn’t change at all, and the over-exuberance of his study partner is one of them.

He sighs and turns as the blond bounces into view. “Nagisa-kun, please not so loud. You’ll disturb the environment.”

“What environment? We’re here to study Haru-chan, and Haru-chan never minds!” Nagisa grins brightly, before grabbing the railing and leaning over it, shading his eyes as he looks for the aforementioned ‘Haru-chan’. “Oh, he’s on his favorite rock again!”

Rei resists the urge to roll his eyes, instead just adjusting his glasses in habit, handing over the binoculars when Nagisa gestures eagerly for them and pulling out his audio recorder instead. They’re lucky to find Haru this early in the day, as while he frequents these rocks for sunbathing often he’s not always so easy to find, and sometimes entire days are wasted boating around the bay looking for one little glimpse of dolphin-tail or glossy black hair. Iwatobi Bay is deeper than it looks, and Haru knows every nook and cranny and is quite adept at hiding from them when he doesn’t want to be watched.

Thankfully, today doesn’t seem to be one of those days, as Haru continues dozing on the rocks and ignores the small boat as it gets closer, finally dropping anchor some fifty meters or so away. It’s actually rather fascinating, as most members of the species  _Homo maris_  are rather skittish of human interaction and flee at the slightest movement.

Their subject, though, seems to be one of the rare individuals who lacks any fear of anything, including the pair of humans who like to stare at him for hours and write things down. Rei doesn’t think he’s seen any other expression on Haru’s face other than apathy, even if the boat is right beside him and Nagisa is chattering loudly. It worries Rei sometimes about what it means for Haru’s survival instincts, but he’s also secretly thankful, since it gives them a chance to study one of the most fascinating species on this planet up-close and personal.

_Homo maris_ , commonly known as mermen or mermaids even though Rei hated the term, were known for centuries in myths and tales but only within the last century were they properly discovered and documented. Intelligent, secretive creatures, they evaded study for decades, and only recently has any progress been made with newer technology and individuals like Haru who aren’t as skittish of their land-going relatives as most.

Rei feels privileged to be on the study team for these individuals, and already they’ve learned heaps of material through the individual they’ve nicknamed “Haru”. There’s still so much more to learn, though, and Rei is excited that every day could lead to some new discovery. Why, after a century of study, it was only ten years ago that they finally discovered that there were two separate subspecies! The thought of what else is waiting to be discovered about these creatures makes Rei wake up early every day it’s observation season.

Rei checks his watch, noting the time, and starts setting up to record.

“Oooh, ooh, Rei-chan, are you going to record? Me too, me too!”

Rei sighs and tries to ignore the blond, clicking his recorder on. ”Ryugazaki Rei, October the second, approximately nine forty-three and seven seconds in the morning.”

"That’s not approximate at all, Rei-chan!"

"Beginning audio observation log number fifty-seven," Rei continues as if he hadn’t heard. "Subject, Haru—"

"Haru-chan!!"

"Subject, Haru." Rei can feel his teeth starting to grind again, he’s going to have to have a dentist look into that. "Gender, male. Species,  _Homo maris_ , subspecies  _syreni_ —”

Nagisa bursts in yet again. ”Subspecies lazybumicus!”

Rei really can’t let that one go. ”Will you please stop trying to name our research subject random things?”

Nagisa blinks his wide eyes, looking completely innocent. Rei doesn’t buy it for a millisecond. ”But Haru-chan’s so lazy! I’ve never seen a mermaid sleep as much as him! He’s got to be a new subspecies!”

"Please don’t use that word, it’s an unscientific gendered noun applied to myths and fairytales, not the natural creature we are studying." It’s a losing battle, but Rei always fights it. "And Haru is not a new species, he’s simply a very laid-back individual."

"No way! I’m gonna file the name when we get back, do you think lazybumicus will fly? Oh, or maybe since I found him, I should name it after myself!  _Homo maris nagisa_ , has a nice ring doesn’t it?”

"Nagisa-kun, please stop trying to create a new subspecies from one individual completely identical to his fellow species just because he’s a bit of a couch potato." Rei’s voice has attained the specific high pitch it only acquires when he’s forced to deal with Nagisa for any length of time. Why were they partners again?

Well, honestly it was because they  _did_  make a good research team, as Nagisa’s spontaneous and quick-witted nature nicely balanced Rei’s own methodical planning ways, but sometimes Rei feels it’s not quite worth the exasperation.

Well, it’s useless recording now. Besides, Haru is napping, so it’s not like it would have been ground-breaking researching material anyways. ‘Subject Haru has yawned, subject Haru has rolled over, subject Haru hasn’t moved for the past thirty minutes and appears to be drooling on himself’…

Sighing, Rei flicks the recorder off and shoves it into his coat pocket. Still, he wishes Haru was doing something other than napping. It’s getting close to the date that Haru seems to disappear for a month and Rei hopes to gain a little more data before Haru vanishes. Researching Haru is more difficult in winter. While Iwatobi Bay is fairly secluded and protected from the elements, storms do occasionally roll in, and of course standing on a boat in freezing weather drains anyone’s strength. Haru himself stays in the bay year-round, but during winter he doesn’t surface nearly as often and days can go by without seeing him at all. Rei and Nagisa generally consider observation season over after the beginning of October, as, for unknown reasons, Haru vanishes completely from the bay for about a month.

They haven’t been able to find out where he goes yet, though. But generally one day during the first week of October he’s gone until sometime early November. It’s strange, as dolphin-morphs like Haru aren’t known to migrate any great distances. Rei once again wishes he and Nagisa had the funding to get proper tagging equipment. If they could just afford to tag Haru, then they could figure out where he goes during this mystery month.

The best guess is that he’s going to mingle with the group of dolphin-morphs that live in the southern end of the bay, more secluded from humans and hard to observe. They must be his relations somehow, but for some reason Rei and Nagisa haven’t been able to fathom yet, Haru tends to swim alone away from the rest of the group.

Nagisa just calls Haru a loner, but Rei wonders sometimes.

“Oh! He’s moving!”

Nagisa’s excited exclamation makes Rei look up from his ponderings. Indeed, Haru finally seems to be stirring, sitting up and stretching. A brief yawn shows a flash of conical teeth, almost identical to the dolphins that Haru’s color morph takes after. After he rolls his shoulder, Haru looks over at the boat, face as indifferent as ever.

“Oh, he’s looking at us! I wonder if he’ll come close today? Do we still have some mackerel to treat him if he does?” Nagisa chatters excitedly, pulling up the camera hanging from around his neck. Even Rei holds his breath a bit as he watches Haru, waiting for what the merman will do.

Haru blinks once, twice, very slowly, watching the boat with deep ocean-blue eyes. And then, without any warning, he launches himself off the rock and slips into the water. The arc of his form is perfect, leaving barely a ripple, and once again Rei is struck by just how  _beautiful_  this species can really be. Even Nagisa is wide-eyed and silent, basking in the wonder of the world’s natural beauty as Haru vanishes into the deep gray waters with no trace left that he’d ever been there.

Then he takes a deep breath and cries out, effectively shattering the moment. “Awwww, that’s  _away_ from the boat! He left us! How mean, Haru-chan! Come back!!”

Rei’s shoulders slump and he winces, adjusting his glasses again. He definitely should look into a new research partner sometime. If only to preserve his ears and sanity.

The surface of the ocean is unbroken, dark waves refusing to give any clues, and he feels that research is over today. They’re not going to find Haru again. Indeed, probably the whole season is over. Rei has a feeling that it’s time for Haru’s mysterious month-long vacation once again.

Rei sighs. Oh well, at least they’ve gotten a lot of data this summer. They’ll just have to wait until next season comes along. He pats Nagisa’s shoulder, who is pouting.

“Come on, let’s go back to shore, Nagisa-kun.”

 

* * *

 

Blue eyes watch from behind a rock as the boat holding the two researchers pulls up anchor and starts chugging back to shore. When he’s certain they’re gone, he submerges again and kicks off, heading for a direction he knows by heart, by deep instinct thrumming through his veins.

Haruka doesn’t mind the Splittails much. Most of his fellow silvertails complain about their giant floats and their strange nets and how they make the water messy, and various other complaints, but Haruka’s found that once you learn how their stuff works, it’s easy to maneuver and live around. He’s certainly never had any trouble in all of his years of life. If you were dumb enough to get hurt by the Splittails then it was your own fault.

The elders like to sing songs about how dangerous they can be, about how they used to viciously hunt down Haruka’s kind, but those days are long-gone. He hasn’t heard of a Splittail actively killing one of them for generations. He’s even learned that floats with a little image of one of their own somehow colored onto their bottoms means that if he pokes his head above the surface he can sometimes get free food. Certain floats even specialize in mackerel, and he tags them religiously.

The float carrying the two Splittails that like to watch him is one of them, they always seem to have a bit of mackerel on hand for him if he comes close. He’s normally tempted, but not today.

Today is Important.

Silvertails don’t migrate. Haruka and his fellows have lived in this one area for generations, and Haruka isn’t going to bother leaving this bay for the rest of his life. However, he makes an exception whenever this season comes along, when the Waterswell and the Palecircle cycles are just right. When the air feels just this cold, when the Palecircle is in just this right position in the sky, Haruka leaves his bay to head out to more open water, looking for a certain current.

Because, this time of year, it’s the time for the blacktails to come through as they follow a seasonal run of fish. The run ends just north of Iwatobi Bay, and once the fish run out, the blacktails leave. And for as long as he can remember, Haruka has met the migration and stayed with them until they left for the colder waters of their home.

More specifically, he comes to meet the migration for just one individual.

At the thought of who’s waiting for him, Haruka swims just a little bit quicker. He doesn’t remember how they met, or even how he had learned of the blacktail migration in the first place, he just knows that every year he _has_  to meet the gentle blacktail with the soft green eyes and gentle smile. Meeting him just once a year and spending all Palecircle with him makes the rest of the year more tolerable.

Haruka doesn’t get along with his fellow silvertails well. They’re flighty, flirty, and prone to following whatever was amusing at the time rather than appreciating what they already had. Haruka hates how superfluous they all are. He doesn’t like how they whisper behind his flukes that he should’ve been born a blacktail if he loves them so much, and then in the same breath giggle and flirt with the migrating blacktails for casual flings. He doesn’t like how they go in packs just to bully the Straighttails who hide in the deeper waters of the bay, even if the Straighttails are a little weird.

Ever since his Elder-mother died, Haruka hasn’t much liked spending time with other silvertails. It’s why he’s glad they don’t like humans. He gets most of his bay to himself to swim and play in without having to maneuver around dozens of other swimming tails chasing away all the mackerel.

But he does like being around Makoto. Everything about the green-eyed blacktail makes Haruka happy. From his soothing voice to his gentle smile to how he treats his little twin siblings. Haruka really really likes Makoto.

And this year is different. This year, he feels even more of an urge to be with Makoto. He’s finally maturing into true adulthood, and it’s time to take a mate. He feels it in his blood, in how restless he’s been lately, how he’s even less tolerant of the flirty females who sometimes try to get him to come back and swim with the pod. He doesn’t want anyone else than Makoto.

So this year he’s going to take Makoto as his mate, whether he has to leave with him or get Makoto to stay here in Haruka’s bay. It’s time, he’s ready.

Haruka lets a rare smile slip onto his face as he swims for the current as fast as he can and counts the tailstrokes until he’s together with Makoto again.


	2. Chapter 2

It takes a Brightcircle cycle and a half of solid swimming to reach the cold current that flows down from the north. Haruka doesn’t bother stopping except to catch a few naps along the way, not even to eat – food is too sparse in open ocean and he’ll be fed plenty when he arrives anyways.

Finally, when the Brightcircle is slowly sinking towards the horizon during his second cycle of travel, when Haruka breaches the surface and takes a deep breath, he hears what he’s been waiting for. The chill sea breeze carries the faint sound of voices singing.

The sound draws new energy out of Haruka, now that he knows he’s so close to seeing Makoto. A kick of his tail launches him into the air as he completes a graceful arc back into the water, using the extra speed to power towards his destination. While his fellow silvertails like to mock him when they think he can’t hear, they all begrudgingly admit that he’s the fastest, most graceful swimmer the pod has seen in a long time. It’s for his swimming skills and his looks that, no matter how many times he coldly rebuffs them, females still occasionally come into his bay and flash their tailfins at him.

It’s annoying. The only thing the females care about is shallow, vapid self-satisfaction by having a productive fling with someone “talented”. Haruka’s never liked that. He was raised by his Elder-mother after her daughter birthed him, a product of the shallow one-time flings that Haruka hates, and then she left him in her mother’s care and swam off and he hasn’t seen her since. He doesn’t even know who or where his father is.

He knows it’s normal. He knows that elders past their own child-bearing days or pairs that have mated permanently are the ones expected to raise the children, while the younger and unattached explore and hunt and do various things that can’t be done bogged down with a child clinging to their tailfins. He knows that any children are children of the pod as a whole, and so it makes sense that anyone living a more stable, sedate life should be the ones raising offspring. His Elder-mother, before she passed, often told him these things. She even gently reprimanded him sometimes, saying that she never knew who her own parents even were and that she was raised by an unrelated pair-bond. He’s lucky that he got an actual relative to take care of him, as there are many that don’t even know who in the pod they’re related to by actual blood.

He may be lucky, but Haruka hates it. It makes him feel like his kind care only for themselves and dump anything inconvenient on others so they can continue leading their selfish lives. His Elder-mother should have led a relaxing end of her life, being cared for by the pod and not having to watch over a grumpy youngling in her waning years just because her daughter didn’t want to do it herself.

Maybe it’s why he started visiting the blacktails. They may be the same people as Haruka’s own silvertails, but their customs are different. They pair-bond far more often, and while there are casual flings between pods, the mother always raises her own young. It’s a sense of family Haruka thinks his own pod could learn from.

He can see their shapes in the water now, outlined against a huge silvery mass in the distance – the migrating fish. As he approaches, several hums and whistles call out to him in greeting. He comes every year, he’s a familiar face to all the blacktails in the pod, and they all welcome him.

The welcome always give him a strange, warm feeling in his chest. It’s nothing like home, it’s better. He allows himself to nod and whistle back a few greetings to those he knows better, more than he does at home, but he continues swimming past the outer ring. He’s heading for the center of the pod, where the families swim. One family, in particular.

They see him before he sees them. The only warning he gets is two high-pitched squeals, slightly muffled by speed and water, before he’s hit by two speeding shapes, little arms wrapping eagerly around his chest and waist.

He has to flail for a bit to right himself, but a smile is already fighting its way onto his face. Two pairs of eyes, one green, one brown, both shining identically, stare up at him with adoration, and Haruka gently pets their heads as he hums at them. They can’t talk underwater, instead regulated to the hunting hums and whistles, but the twins are doing their best to try anyways, high-pitched repeats of his signature whistle sounding over and over, occasionally interspersed by bubbles as they get a little too excited and blow out air, still a little too young to be completely in control of themselves.

Mildly worried that they’ll expel all their air trying to babble at him underwater, Haruka wraps his arms around them and pulls them towards the surface. As soon as they break out into the air, he’s assaulted by noise.

“Haru! Haru! Big brother Haru, you came!! We were waiting but Mama said you might not be here until tomorrow if the waters were bad but I knew you’d be here today!!”

“What are you talking about!? I was the one that said Haru would be here today! You argued with me all yesterday about it because you agreed with Mama and got scared cause the skyshapes were dark!”

“I did not! I believed it, you didn’t!”

“Did too!”

“Did not!!”

“Ran, Ren.” Haruka breaks into budding argument. While he loves Makoto’s twin siblings dearly, their constant bickering is something he misses far less when he’s actually there with it. “I’m here anyways, don’t argue about it.”

Two heads bob in enthusiastic agreement. “Okay, big brother Haru!”

Haruka smiles, petting their little heads again. Really, so energetic. He doesn’t know how Makoto’s mother had the energy to raise them at the same time. Still, they were very sweet and adored him to bits, and Haruka couldn’t help but feel they were his own siblings as well, so he continues to smile and nod at appropriate points when they start babbling again, about a pretty seashell the female Ran found the other day, or male Ren’s newest bubble-blowing record. Noisy, but it was a good kind of noisy. Haruka didn’t mind this kind of happy, loving noise.

He’s so absorbed in the twin’s babble that he doesn’t hear the soft sound of a gentle break in the surface water behind him. He only notices when both of the twin’s attention is grabbed by something behind him, lighting up their eyes, and he looks over his shoulder to meet gentle green and his breath catches in his throat.

A smile as sweet as the look in those eyes slowly stretches over Makoto’s face. “Haru.”

Haruka lets out the breath he was holding, feeling something deep within him unwind. This is what he swims two cycles for, what he lives for meeting every year. He’s turned around and moved to Makoto without even realizing it and their hands link together naturally, like the two halves of a clam shell.

“Makoto,” he breathes, and the smile and small squeeze of their hands he gets in return send warmth through him like sea foam bubbles.

Whining comes from behind him. “No fair, big brother! You always steal Haru!”

A splash follows, Ran must have thrown water into Ren’s face if the angry sputtering is any indication, Haruka is too entranced to look away from Makoto just yet. “Silly, they’re mates, of course big brother is more important to Haru!”

Makoto laughs, red flushing his cheeks and ears a little bit, and Haru watches in avid fascination. “Ran, Ren, don’t fight…a-and we’re not mates, don’t m-make assumptions! You’ll embarrass Haru!”

When those words come out of Makoto’s mouth, Haruka refocuses onto his goal. Right, they weren’t technically paired – although Haruka’s pretty sure everyone in Makoto’s pod pretty much consider them so anyways, as the twins just proved – and he came this year to right that wrong. He’s not leaving this time, not unless Makoto is coming with him.

He leans closer, closer than he usually gets because the instincts thrumming through him this year are making him feel especially bold. The red spreads, and Haruka thinks Makoto really looks adorable with red cheeks. It’s a look he likes. “It only embarrasses me because it’s not true when it should be.”

A bit blunt, but Haruka’s never been one to mince his words, and he doesn’t have to be embarrassed about something he’s wanted for his whole life, it feels like. Makoto is now red enough to rival the sinking Brightcircle melting into the horizon.

“H-Haru…” He whispers, eyes wide and shining in the light.

Haruka inches closer, letting the swell of a wave press him full against Makoto, and there’s barely a finger’s width of space between them. Just a little more…

Seawater suddenly fills his vision, and he pulls back in surprise, coughing a little from the sudden intrusion. Makoto is equally drenched.

“Geez, big brother, Haru! Stop doing mating ritual stuff in front of everyone! It’s embarrassing!” The culprits reprimand them both, Ran with her arms crossed over her chest and pouting at Makoto and Haruka, and Ren looking apologetic but his lips are still pulled into a pout.

Haruka is a little annoyed at being interrupted, even if it is by Ren and Ran whom he sees as real little siblings, but Makoto just laughs softly, and the sound causing relaxing little tingles in Haruka immediately. “S-Sorry, Ren, Ran.”

Makoto’s face is still bright red, and while they’re obviously not getting any further with the twins looking on, Haruka is content. He knows he’s gotten his point across, especially as Makoto’s fingers are still intertwined with his, and when those green eyes meet his own again, filled with warm emotion, a gentle squeeze on his fingers makes Haruka’s chest do the warm bubbly thing again.

Haruka allows himself to squeeze back, feeling an answering smile slip across his face as Ren and Ran scoot in-between them and start demanding attention again. They have to let go of one hand to allow the twins in, but their other hands remain firmly tied together. This is fine, too. This is more his family than any amount of silvertails could ever be.

Still, he thinks to himself as they dive back underwater to follow the twins to meet up with Makoto’s parents, Haruka reminds himself that he’s going to make sure he continues with Makoto later.

Preferably after dark, and the twins are safely asleep to not throw water into their faces.

 

* * *

 

Nagisa slumps across the cafe table, making an impressive impression of a boneless sea slug as he whines. “Noooo, I don’t want observation season to be over!! What am I going to do all winter!?”

Rei sighs, pushing up his glasses. “You could always help me with transcribing our data for once, so that it doesn’t take me an entire week…”

“Don’t make my winter more boring, Rei-chan. I’m a person of action! I get results, you file the results! It’s how our amazing teamwork functions, after all!” Nagisa puffs out both cheeks into a ridiculous expression. “But now Haru-chan’s gone and it’s sooooooo cooooold. I’ll have to spend the winter researching in the penguin exhibit again! Winter is so boring!”

Rei mentally resigns himself to having to do all their paperwork by himself, again. No matter how much he complains, Nagisa will never do his own paperwork, which is probably the only thing stopping Haru from being filed as subspecies lazybumicus. As long as Rei has to do everything paper-and-form-related, Haru is safe from embarrassing renames. That’s not going to stop Rei from complaining, though. “Well, since I’m the one saddled with the even more ‘boring’ practical things, I don’t think you have any room to be complaining to me, Nagisa-kun.”

“Nah, I bet you find it fun, Rei-chan, and if I did help you’d probably get really mad because I mess with your system. ‘I have calculated the theory for maximum paperwork efficiency, Nagisa-kun, and you’re not doing it beautifully enough!’” Nagisa’s voice deepens as he launches into a bad impression of Rei.

“I would not, and I’ve told you a million times that I do not sound like that!” Rei exclaims instinctively, but mentally notes to himself that yes, having Nagisa in the office with his paperwork would probably cause a lot of headaches and mess up Rei’s delicate system. Not that he’s going to admit that. However, in the interest of preserving his paperwork fortress of solitude, Rei decides a change of topic is in order. “Why don’t you try to do some more practical research? Surely seawater samples or analyzing underwater sounds is more interesting than watching the penguins at the zoo again. I don’t even know how you’ve been able to convince the university board that you’re doing legitimate research.”

“Ugh, are you kidding me Rei-chan!? Staring at boring slides or listening to a bunch of static-y water sounds is way more boring than watching penguins. Penguins are cute! If mermaids didn’t exist, I totally would be a penguin researcher. Their little hops are so cute!”

“Please call them mer _people_ , at least, Nagisa-kun, they’re got two genders.” Rei mutters, pushing up his glasses again. “Why didn’t you go into penguins, anyways? It would suit you.”

Nagisa sits up and straightens out, eyes going bright. “Well, yeah, I thought about it because I do love penguins, but really, mermaids! It’s a fairy tale brought to life, don’t you think? And we know so little! How did they evolve? How did they end up identical to us, but in the water? Why do some have shark-like tails and some have dolphin-like tails? Are they really just as intelligent as we are? There’s just so many mysteries! It’s so exciting, just watching them, thinking that any moment I could see something that no one has ever seen before, ever! I’m capturing little bits of history, little bits of mystery, and it makes me feel like I’m a part of something a lot bigger than just research, you know? It almost feels magical. Sure, penguins are cute and all, but there’s nothing really new to learn about them, is there? They’re pretty well-documented. With mermaids, even if it’s just some photos, I’m always contributing something new and special to the history of science and helping to preserve them even better, so everyone can know them! I want to share Haru-chan with the world!”

Rei is rather surprised as Nagisa babbles on, arms flailing in excited gestures. Nagisa has always been exuberant, sure, but he’s not quite sure he’s seen him this  _passionate_. Obviously the blond feels strongly about their research subject. It makes Rei a little happier – for all of Nagisa’s annoying tendencies and eccentricities, he at least is truly devoted to their work.

Nagisa turns to look at Rei, eyes still shining. “Hey, Rei-chan, why did you get into mermaids? I’d think someone like you would be more into writing tons of dull research papers about cosigns and stuff, not a marine biologist.”

“Merpeople,” Rei corrects again, before flinching. He just knows he shouldn’t say, for some reason. “N-No special reason! I just happen to be very interested in this branch of study, just because I am good at formulas does not mean I have to go into mathematics.”

“Boo, Rei-chan, that’s not an answer! Come on, I told you mine, tell me yours!” Nagisa is now leaning over the little round table, and Rei knows he’s not getting out of this unless the cafe literally catches fire. And then Nagisa would probably bring up later. “You’ll laugh, Nagisa-kun. I do not want to be laughed at.”

“What? I won’t laugh, I’m not mean, Rei-chan!” Nagisa pulls a pout that a twenty-five-year-old person out of grad school shouldn’t be able to make. It makes him look ridiculously young. “Pleeeaaaassssssee?”

Rei scowls, flustered, looking away and adjusting his glasses again. “I said no, Nagisa-kun!”

“No! I really want to know, Rei-chan! Please? It’s only fair!”

Rei makes a strangled noise because he knows he’s lost. Nagisa will never let it go and honestly it’s better to just get it over with. Nagisa will laugh, but it will be out there and quick instead of days of whining like this. Like a band-aid, really, perhaps it was best to get over with it quickly. “Fine. But if you laugh, I won’t tell you anything more!”

Nagisa immediately flops back into his chair, bobbing his head enthusiastically like a baby bird. “I promise, Rei-chan!”

Sighing, because why did he allow the conversation to come to this, Rei adjusts his glasses yet again to try to hide his flush. “…When I was little, in fifth grade…we went on a seaside swimming trip. I couldn’t swim very well at the time, so I decided to keep training after the day ended. I snuck out at night to swim in the ocean, because I was young and foolish. Unfortunately I got in a riptide and nearly drowned, but something pulled me back to shore. When I looked back to the water to see what saved me, all I caught was a figure doing a arching jump back into deeper water. It was only a flash, but I recognized a merperson. It was imprinted onto me, that one moment of that merperson hanging weightlessly in the air, framed by moonlight against the stars…it was very beautiful. I felt that I had to see that beauty again, and…and share it with the world, like you, I suppose.”

His little story drags to a halt, and Rei is quite sure he’s bright red. It’s not something he’s told anyone before, after all. He mentally counts down the seconds until Nagisa bursts out laughing because he always laughs at Rei’s sense of beauty. Three…two…one…

“Awwwww, Rei-chan! That’s so sweet, I didn’t know you could be that sweet!” Rei looks up surprise, because that’s definitely not laughter.

The way Nagisa is staring at him, eyes wide and shiny, though, is almost more embarrassing than if he had just laughed. “I-It’s nothing, just…what I felt…”

“No, what you felt really was beautiful! That’s so sweet, thank you for sharing it with me, Rei-chan! I’m glad you’re my partner!” Nagisa smiles, doing a great sunshine impression with his sunny expression. “Do you ever want to meet that mermaid again? Maybe it’s destined love! Was it a boy or a girl? A  _syreni_  or  _erectucaudus_? What color tail did they have? Maybe we can find them for you, Rei-chan! Wouldn’t that be romantic?”

“I…what?” Rei isn’t quite sure when the jump in logic occurred from  _merperson encounter_  to  _destined lovers_. Nagisa’s thought processes mystify Rei. “Nagisa-kun! I am not in love with a merperson! Besides, it would be a biological impossibility, we don’t live in the same habitats, and we’re probably not even reproductively compatible! It was just an instant impression, anyways!”

“But that’s boring, Rei-chan! Just think of the research we could do! And isn’t it just like that fairy tale  _The Little Mermaid_? Don’t you want to live in a fairy tale, Rei-chan?”

No. No. Rei is not getting dragged into this. Nagisa can pester Rei into a lot of things, but trying to make him copulate with a seafaring organism that Rei is studying  _scientifically_  is just not going to happen. “The mermaid died at the end of that fairy tale, Nagisa-kun, why would I want to live in that story!? And no! We’re not going to be doing any sort of romance, we are here for research! No fairy tales!”

“Rei-chaaaaan!”

It’s shaping up to be another long session of Nagisa pestering Rei – but he will not give into this one,  _no way_ , ugh! – but he is thankfully saved from evil blond clutches by the jingle of the cafe door bells and a booming voice. “Why, if it isn’t Ryugazaki and Hazuki! Long time no see!”

Both Rei and Nagisa look over in surprise. Walking over to them with a grin is a familiar redhead. Nagisa grins back excitedly, waving him over. “Sei-chan!! You’re back in Japan!”

Rei is more subdued, but he smiles nonetheless. “Mikoshiba-san, it’s nice to see you well.”

Mikoshiba chuckles slightly. “I always tell you to drop the ‘san’, Ryugazaki, makes me feel like my father. I’m no stuffy old businessman. Anyways, how have you guys been? Research going good? I’m here teaching an old underclassman some ropes about research.”

He turns, waving someone closer, a slim young man with silver hair and bright blue eyes, delicate face carved into a fairly nervous expression. “Come here, Nitori, have you guys met? Ah, don’t think so, have you? Anyways, Nitori, these two are some grad students I lectured, they do some nice work here in Iwatobi about _syreni_. Ryugazaki Rei and Hazuki Nagisa! This is Nitori Aiichirou, fresh out of grad school and my new little remora to teach. He’s an  _erectucaudus_  specialist, we’re actually here to study the population of them in Iwatobi Bay, so we’ll probably be seeing a lot of you guys this next year once spring comes around. As you’re all my underclassmen, I hope you guys get along!”

The named Nitori gives a deep bow, voice earnest. “P-Please take care of me! Thank you very much!!”

Nagisa’s grin stretches wider, eyes shining. Rei wonders if perhaps that’s a bad sign. Nitori looks like a very earnest, nervous sort of person, and Rei’s not sure how he’ll react to Nagisa’s…uniqueness. “Nice to meet you, Ai-chan! I can call you Ai-chan, right? I’m Hazuki Nagisa but you can call me Nagisa or Nagi-chan or anything you like! Just not Nagisa-chan because that’s reserved for me in a dress and I hate it. Let’s get along!”

Rei can almost see Nagisa’s enthusiasm hit Nitori, like a physical punch. “U-Um…A-Ai-chan…? Um. Okay…? Ah!! Yes! N-Nice to meet you!”

Deciding to save the poor kid – and prove that no, they’re not all lunatics like Nagisa – Rei clears his throat and smiles politely. “I’m Ryugazaki Rei, it’s nice to meet you. I look forward to working together.”

“Y-Yes!!” Nitori flings himself into a bow again, and Rei is mildly concerned that he might give himself whiplash one day. “Please take care of me!”

Mikoshiba pats Nitori on the back, a little too roughly and he stumbles forward a step. “No need to be so polite, we’re all on the same level from now on. Anyways, Ryugazaki, Hazuki, I guess your observation season is over? Otherwise you guys probably wouldn’t be lazing around in a cafe like this.”

Nagisa fell instantly into a pout. “That’s right! Haru-chan’s left on his mystery month trip again, so we’re going to have to wait until March or April to see him again. I really wish we knew where he was going! He always disappears for October and I’ve never heard of a  _syreni_  doing that.”

Mikoshiba strokes his chin thoughtfully as he pulls out one of the empty chairs at the table, taking a seat. After a moment, Nitori hesitantly sits down at the table with them. “Hmmn, Haru-chan is your  _syreni_  subject, right? That is weird, I’ve never heard of a dolphin-morph like him migrating. An individual might switch family groups for a mate or to thin the blood a little, but I’ve never heard of one making a regular, yearly migration. You guys have no idea where he goes?”

“Absolutely none!” Nagisa does his best to impersonate a chipmunk as he pouts. “We would tag him, but we’re just a little group funded by the local university. We have just enough to go on our trips, we don’t have any funding to spare for tagging equipment.”

“That’s a disappointment.” Mikoshiba nods in agreement. “Too bad I didn’t run into you guys before Haru left, me and Nitori have tagging equipment for our study and we could have lent you some. I’d be just as interested in finding out where he goes.”

Nitori speaks up. “Is this…Haru-chan…your research subject? He’s a  _syreni_?”

Nagisa beams happily. “That’s right! Haru-chan is one of Iwatobi Bay’s resident syreni, and the only one that lives in the bay proper close to people! He’s this huge oddball who lives alone and disappears every October. Male  _syreni_ , dolphin-morph, we’re guessing late teens to early twenties, it’s hard to pin down age. We’ve been watching him for two years now! He recognizes us and even sometimes comes up to the boat for mackerel! It’s his favorite. He’s also super-lazy! I think, cause he’s so weird, that he’s a new subspecies, but Rei-chan won’t let me file it.”

“That’s because he isn’t a new subspecies, Nagisa-kun, I’m not letting any subject I’m looking after be named lazybumicus.” Rei cuts into Nagisa’s babble before he talks poor Nitori’s ear off. Nagisa pouts at him, but Rei gracefully ignores it and turns back to Nitori. “Anyways, Nitori-kun, Mikoshiba-san said you were an _erectucaudus_  specialist?”

Nitori blinks in surprise, apparently not expecting to be addressed, before nodding eagerly. “Oh! Yes! I am! They’ve always fascinated me a lot and I’ve always wanted to do research on them! They’re so mysterious, since they tend to live at deeper depths than  _syreni_ , you know. When I heard that my hometown bay had a population of them that wasn’t studied at all, I just had to come back home to research them! Mikoshiba-senpai was kind enough to accompany me back and help me get started.”

Mikoshiba waves a hand lazily. “Not so much, I just felt like coming home for a bit. Overseas research gets a little tiring, you know? Besides, I’ve studied  _syreni_  for a while, I’d like to get to know our sharky types better. I hope to get in the water with them before next year is over. They’ve got such an elegant, powerful way of swimming, it’s really a different look, should make for some amazing experiences.”

“How it’s like to swim with mermaids, Sei-chan? I hope to swim with Haru-chan one day, but it’s kind of hard to predict when he’ll get his lazy tail off his rocks and actually swim. He’s so lazy!” Nagisa leans over the table again, eyes sparkling in curiosity.

The redhead blinks, then leans back in his chair, hand on his chin in thought. “It’s a real different experience. Kinda like dolphins, I guess? Easier to read, but harder to reach. Dolphins’ll come closer cause they’re curious, but, well, our merfolk subjects are skittish little things. So if you get to swim with them, it’s great, since it means they trust you.” Mikoshiba suddenly barks a laugh. “Sometimes too much. This one girl down in Suriname kept flashing her fins at me, obviously looking for a little different fun, and while I’m flattered such a pretty lady showed me such regard, well, I don’t think it would work so well! But I hope I get that trust again here in Iwatobi. I’d love to get to know my hometown neighbors, you know?”

“It sounds so fun! Maybe you can let me tag along on some of your trips when Haru’s too busy trying to turn into a barnacle. Or would that be Harunacle? A barnacle that’s a Haru!”

Rei groans. “Please, no more puns, Nagisa-kun.”

“You’re no fun, Rei-chan! My puns are the pinnacle of barnacle entertainment, they’re always on top of things, after all! I’m sure they’ll grow on you!”

That one causes Rei to physically wince and Mikoshiba bursts out laughing. Nitori looks extremely dazed, as if he can’t quite process what just fell out of Nagisa’s mouth, and Rei feels sorry that Nitori’s first introduction into field work is through Nagisa. He hopes the poor guy doesn’t quit halfway through the summer from pun exposure alone, always a hazard working with one Hazuki Nagisa.

Rei just covers his eyes with his hand. Spring needs to come faster before he goes insane.


	3. Chapter 3

“Will this really attract any  _erectucaudus_  closer, Sei-chan?”

Rei looks up from writing down water temperatures when Nagisa voices his question, as that's an answer he'd also like to know. While he trusts his senior, more experienced biologist, tossing hunks of raw beef into the ocean water isn't in any university training manual. Also, the calendar recently ticked over to November – still no sign of Haru in the bay from the unpaid watches Rei sometimes takes from the shore – and a cold front has blasted across the water in the last few days. He'd rather not stand around on a boat in this wind unless it's for a proven method.

Mikoshiba tosses a grin over his shoulder as he ties a nylon rope around another beef haunch. “You betcha. This'll drag any lurking  _erectucaudus_  right to the surface, but not as many sharks as normal chum. Perfect to study and maybe tag one without accidentally tagging an actual shark.”

Nagisa leans over, making an impressed noise as he watches the hunk of meat get tossed into the waves. “Really? I thought sharks would come for any sort of blood.”

It's Nitori who speaks up to answer this time. “We'll certainly get normal sharks investigating, yes. But on the whole most sharks have a fish diet, and a shark's sense of smell is quite acute. Beef and its blood is very different from their normal food so they aren't as keen to investigate it as they would be for fish blood.  _Erectucaudus_ , however, can't tell the difference and will come to investigate any blood.”

“Even though they're shark-morphs?”

Mikoshiba stands up, dusting off his hands. “Yep. You gotta remember, all these different tail shapes and colors we call morphs are just that – colors and shapes. They're mimics designed to imitate the largest ocean predators to keep themselves safe. But they don't have a close genetic relationship to the animal they're mimicking.  _Syreni_ , for example, hum, sing, and click underwater like dolphins do, but it's just an imitation – they don't have any actual sonar, it's just for communication purposes since they can't talk underwater. So an  _erectucaudus_  may look like a shark, but they don't have all the same adaptations a shark would, and in fact don't smell much better than we do. So they can smell this blood a bit farther away than a  _syreni_  could, but they can't tell what kind it is. It's just blood to them and attracts them no matter what it comes from.”

“I see,” Rei murmurs, walking over to the boat's railing to lean over and watch the meat bobbing in the ocean. “ _Syreni_  dolphin-morphs, or Haru at least, feed almost exclusively on fish. Are  _erectucaudus_ different?”

“It's not entirely a separation in actual diet. All  _Homo maris_  generally can eat the same things, but it's separated on lifestyle.” Mikoshiba moves to the cabin, disappearing for a moment before he brings out a sketchbook, opening it to an illustration of several  _Homo maris_  morphs. He taps his finger on the dolphin-styled one. “See, your dolphin-morphs live almost exclusively in shallow, clear seas. They're probably the least tolerant about changes in their environment. They're surface to midwater feeders, generally exclusively on schooling fish. Because they don't have sonar or any better sense of smell in the water than we do, they hunt mainly by sight, so brightly-lit, clear water is important to them.”

Mikoshiba slides his finger down the page to the largest illustrated  _syreni_ , a black and white orca-morph. “Orca-morphs, here, are the most widespread in terms of habitat, like actual orcas. They'll live a little deeper than the dolphins, a little farther out to sea since they're usually a bit larger and stronger. Because of their wide range, they're the least picky and will generally take anything they can kill, although certain populations will stick to certain foods. Any orca-morphs in these waters, for example, will likely take schooling fish, seabirds, shellfish, maybe a turtle or two if they get adventurous, but it'll be mainly fish. They don't compete with dolphin-morphs and  _erectucaudus_  much, since dolphin-morphs stay closer to the shore and  _erectucaudus_  are often deeper. Up north, however, they have to compete with the fish-eating narwhal morphs and the bottom-feeding beluga-morphs, so they'll take to seabirds and seals almost exclusively. Southern populations, on the other hand, might live on penguins. So the orca-morph diet depends on what is most abundant in their traditional pod range.”

Now Mikoshiba moves his finger to the illustration of an  _erectucaudus_ , striped like a tiger shark. “Our sharky friends, on the other hand, are pretty much exclusively bottom feeders. They live deeper than the  _syreni_ morphs, probably to escape competition at the surface. So shellfish, octopus, lobster, flounder...anything bottom-dwelling they'll take. Have some nasty-strong jaws on them too. But they're also scavengers, opportunists who'll take anything edible if they come across it. Not nearly as picky as the  _syreni_  morphs. So, if they smell any sort of blood in the water, they'll come see if they can eat it, while  _syreni_  will stay away from any blood that's not from their own feeding, and sharks tend to avoid mammal blood. So, chumming the water with beef or pork will usually get us at least one  _erectucaudus_ , as long as it's close enough to scent it.”

“Whooooaaaaa, cool!” Nagisa chirps, eyes wide. “Sei-chan's so cool, you know everything about mermaids!”

The redhead bursts into a boisterous laugh. “If I did, then I'd be out of a job! I'm getting paid to learn more, after all! Now then, we've got some bait in the water, so it's just a waiting game. Nitori, how's the radar look?”

“Ah, yes! Just a moment!” Nitori scrambles into the boat cabin to look at the screen of the fishing radar attached to the boat. “Nothing large yet!”

“All right then, keep an eye on it. Anything a meter or over shows up, we might have ourselves a visitor.” Mikoshiba nods, then sits down on the stern of the boat, next to the ropes trailing into the water. “It'll take a bit for the smell to get deep enough, anyways.”

Nagisa hops over and plops down next to Mikoshiba. “So, what else can you tell us about  _erectucaudus_ , Sei-chan? We're helping you over the winter, after all! We should know more about them!”

“Hmmn...” The older researcher strokes his chin in thought. “Well, we don't know too much about them. Since they live deeper than  _syreni_ , you can't just park a boat on the surface and watch a few with binoculars. They're more secretive, too, so they'll only surface to sun themselves and such when no humans are around. So studying them tends to be more of a hit-and-miss luck game than actual researching. In fact, this method to lure one closer was discovered only recently – it seems they're actually pretty food-aggressive, so they'll come to the surface despite the boat if there's food. And only if it's in bays like this.  _Erectucaudus_  in bays are usually all juveniles, the adults are nomads and travel hundreds of miles up and down the coasts and are way more skittish.”

“Wait, only juveniles? So this is like some kinda breeding ground?”

“We assume so, from past behavior studies.” Nitori's voice comes from the cabin. “All  _erectucaudus_  found in bays or other sheltered areas for longer than a month have all either been under twenty years old or mating adults. The adults will stay in the bay until the children are weaned and able to hunt on their own, then they leave. The offspring then swim in small schools until they grow old enough to leave.”

“Whoa, that's really different!” Nagisa chirps. “So they don't...oh?”

The blond scientist's words are cut short when a coil of one of the nylon ropes suddenly starts whirring, being dragged quickly off the boat and into the water. Mikoshiba stands up, grinning sharply.

“Looks like we have a taker! Nitori, check that radar!” Nitori yelps an affirmation, sounding like he's dropped a ton of papers in the cabin as Mikoshiba grabs the rope and starts hauling it in. “Good thing it's cold and I wore gloves!”

“Mikoshiba-senpai! Three large objects are on the radar! Two are rising fast, the third is staying near the bottom.” Nitori's anxious voice echoes from inside the cabin.

Nagisa hops to his feet as well, bouncing on the balls of his feet. “Sei-chan, Sei-chan, how do I help!?”

“Oof...” The older man grunts a little, putting a foot against the side of the boat to get more leverage. “Rather feisty. You can help me pull this in, you're wearing gloves right? Ryugazaki, get a camera ready!”

“Ah, yes!” Rei jerks a bit out of the shocked stupor he'd been in, hurriedly grabbing the small camcorder they had brought along for this very purpose – any recording footage of erectucaudus was, apparently, very valuable. Turning the device on, Rei holds up it up and focuses on the end of the rope in the water, slowly being hauled in by the combined efforts of Mikoshiba and Nagisa.

Slowly, after five minutes of hauling, the first prize is a pair of pale, delicate hands, wrapped around the nylon rope and slowly emerging from the water. When they break the surface and touch air, they let go, darting back into the depths, and Rei thinks for a moment that they've lost the opportunity.

However, Mikoshiba remains focused on the water, letting the beef float on the surface, and after one long minute something stirs.

For a moment, Rei thinks it's blood. Deep red pools under the surface of the water like a spreading stain, and Rei hopes that the supposed _erectucaudus_  hasn't been attacked by a shark in a moment of vulnerability by the scientist's actions.

But the blood flows, sliding towards a center point and forming into a long ponytail of deep wine-red hair, pulled back by what looks like bright blue shells and attached to a pale face now peeking out of the water, just up to a pair of pretty almond eyes the same color of the hair.

Mikoshiba grins brightly. “Looks like we reeled in a beauty! Wonder if she'll come closer?”

The older scientist gently tugs the hunk of beef slightly closer to the boat. The apparent female watches closer, slowly pulling more of her face out of the water. In human terms, she'd be quite attractive, and looks to be maybe fifteen years old or so in human terms, with a cute face and slender neck that flows into small shoulders and breasts slightly obscured by the dark water. After a moment, she slides forward through the water, following the hunk of meat.

“That's it, that's a good girl, we aren't gonna hurt you. Hmmn, looks about sixteen I guess? Not old enough to leave the bay yet, as expected. If we can get her eating, we can tag her.” Mikoshiba leans out over the water, slowly pulling in the rope. “Come on, just a little closer...is the equipment ready, Nitori?”

“Ah, yes, just a moment!” Padding footsteps are running towards one of the duffels on board, but Nitori doesn't get a chance to ready the equipment, as just as he reaches it Mikoshiba lets out a startled yelp and jumps backwards.

Rei just manages to get the event on film – right under the scientist's hands, another  _erectucaudus_ breaks the surface, but with a much different temperament. It's only through Mikoshiba's quick reflexes that he doesn't get teeth in his wrists, as the new specimen clacks his teeth shut on empty air instead.

The new arrival stays above the surface for a moment – it's an apparent male, with a harsher face than the female behind him, who calls out something in the Homo maris language when he breaks the water. They're related, if the fact that they share the same dull blood coloring and slanted eyeshape, except the male's temperament is decidedly not as placid, as he snarls at the researchers with a guttural voice, showing off a mouthful of bright white, jagged sharkteeth. Then, quick as lightning, he turns, diving sideways into the water. For a moment, Rei catches a glimpse of sleek, stripe-dappled grey flank before a powerful tail sends a rush of water onto the boat and right into Mikoshiba and Nagisa's faces.

In a flash, the female is gone too, looking as if she's been pulled under by the male, and the ripples of their departure swirls into the waves until no sign exists that they'd ever been a pair of erectucaudus at all.

Mikoshiba, still sputtering out a bit of water, barks out a laugh. “Well, looks like someone's a little feisty!”

That is, Rei thinks, perhaps the greatest understatement of the year.

* * *

 

After a Palecircle of good eating, the migration of fish is starting to dwindle and head into open ocean, too far from the land to bother chasing. Soon the pod of blacktails will reverse their path, heading back north for the cycle of cold air and white shores. For now, they lazily circle the few remaining schools, with less effort in hunting now and more spent fixing the tales of this migration into the podsong.

Soon, Haruka will have to depart from the pod to return to his bay...or join the blacktails and move north with them. What will happen will depend entirely on Makoto's answer.

Haruka's made his intents obvious – he wants a mate this year, and he wants Makoto. For the past Palecircle he's swum as close as possible to the blacktail, dorsals and flukes occasionally brushing each other in faint touches of skin that make Makoto go red in the face and makes the members of Makoto's pod give them knowing looks. That makes Makoto's face go redder and the corners of Haruka's mouth curl up.

They hold hand, and share air occasionally – when the twins don't see them and whine about being showy with their mating rituals, that is. When the light fades and the pod heads for the rocky shores for sleep, they find a crook of their own in the rocks, pressed together head to tail and grooming each other with soft licks and careful fingers, cleaning each other of the day's stresses.

Haruka knows, and he knows that Makoto knows, that they are all but bonded. The only thing missing is the ceremony.

And, well, the answer to one important question.

That night, lying together in their usual spot, Haruka gathers his thoughts and courage to ask the question he needs to. He trails his fingers down Makoto's side, dancing over the place where tan bleeds into black and wide, earning himself a delicious little shiver from the blacktail and a gentle nibble before Makoto resumes grooming his neck. Eyes closed, head tilted to the side, Haruka enjoys the feel as he thinks of what to ask.

Finally, he shifts slightly, curling his tail around Makoto's thicker one. “...Makoto?”

“Hmmn?” Makoto moves to nuzzle the side of Haruka's face. “What is it?”

Haruka sucks in a breath. He can do this. They're basically already mated, he just has to pick out the details. “...The season is ending soon, and then your pod will leave. So...”

Makoto is quiet a moment, before starting to gently stroke Haru's back, fingers running up and down his dorsal. “...That's right.”

Another breath. “So...this time...I'm going home with a mate...or not going home at all.”

He stares down at the lapping water at the bodies, faint ripples highlighting by Palecircle light. His statement means a lot of things – he's going to take a mate this time. He wants, no, needs Makoto for that mate. And either Makoto comes home with him, or he's going with Makoto's pod.

Either way, this time, he's not going to swim away from Makoto. He doesn't want to leave this warmth behind again this year.

Gentle fingers slide under Haruka's chin, lifting him to meet Makoto's eyes – green glimmers in the faint light, like the hard clear stuff that splittails make – sometimes it ends up in the ocean, pounded into a foamy color by the waves and sharp edges turned sleek. Makoto's smile is soft. “What does Haru want?”

He pushes his head into those fingers, closes his eyes. This, he wants this forever, no matter what. But...if he's honest with himself, he wants to go home as well. If Makoto wants it, he'll follow him to the depths of the sea, but Haruka is a creature of habit. While he doesn't always like the inhabitants, the bay is his home and it always has been. He knows every rock, every piece of seaweed, every fingerlength of sand on the bottom. Makoto's home farther north is colder, deeper, with harsher waves and craggy shores that aren't so good for sunbathing the days away. He'd go, if it's what Makoto needs, but...

“I want to make my home Makoto's home,” he murmurs into the warm palm against his cheek.

Makoto's thumb rubs gently across his face. “Then that's what we'll do.”

Haruka opens his eyes to look at Makoto in worry. He knows he's selfish, but he wants to make sure Makoto is happy with this decision too. “Are you sure?”

It's their first big decision as a pairbond, after all.

Makoto laughs softly, leaning forward to press his lips against Haruka's cheek. “It's a little scary, but I want Haruka to be happy. I want Haru's home to be my home too. Besides, it's not like I'm leaving my family forever – we can still meet them every fishrun. And it's not that far away, maybe a swim of seven or so Brightcircles. I want to see Haru's home.”

Haruka isn't entirely sure, since he still feels a little selfish, but Makoto learns forward to press his lips against Haruka's own. “Tomorrow, we'll talk to my mother about the ceremony, okay? Before everyone leaves. And then...we can go home together.”

Home together. It sounds nice.

Haruka closes his eyes and presses back as they continue to share air, tongues melding together and fingers tangling in each other's hair. These fingers move from hair to shoulders to sides, exploring each other's bodies in careful touches. With the important decision out of the way, it feels more final. They will be well and truly pairbonded tomorrow, so finger dip and touch and explore in places they haven't let themselves touch before, sparking a more intense, deeper passion than light flirty skin-touching ever could. Looking down at Makoto sprawled against the dark rocks, green eyes shining like light through the water as it feels like their bodies are melting into one, Haruka has never seen anything more beautiful.

Tomorrow they will be bonded, and then in a few Brightcircles they will head home together.

 _Their_  home.


	4. Chapter 4

The Palecircle dawns clear and bright. It's a good omen for a bonding ceremony, or so Elders say.

Haruka supposes it good that one thing is going right, because his nerves have convinced him that everything else won't. He's sitting in a kelp bed, plucking one long strand to seaweed to bits as everyone in Makoto's pod rushes to prepare for a bonding ceremony.

As promised, Makoto had gone to his mother first thing in the morning with their intentions, hand in hand with Haruka. She had listened to Makoto's stilted but earnest declaration in silence, a knowing smile on her face. When Makoto ground to a stuttering halt, face bright red, she'd reached out and patted his cheek gently. “I knew this day would come, from the very first time little Haruka showed up here, lost and alone and you took him in. I knew there would be something special between you two.”

 _Something special_. Haruka pauses, watching a green bit of kelp float away in the current. His Elder-mother had said the same thing often, always watching with a knowing look when Haruka swam away to meet the blacktails. “That child is the only one you ever keep promises to,” she'd said several times.

It was true. Haruka had always been known for his rebellious free spirit, even back then. He was the child who swam out of the hunting group because being directed on how to swim grated on him, even just for learning. He hadn't wanted to learn to rely on others to get his own food, anyways, so he'd learned how to hunt mackerel on his own and had been happier for it.

Of course, even through that, he remembers not being so opposed to grouping up with Makoto in _his_ learning expeditions. Indeed, any activity that Haruka thought of as restricting or opposing became the exact opposite in the presence of the gentle blacktail. Swimming beside Makoto made Haruka feel like he was flying free instead of cornered and crowded like others.

Special, indeed.

His signature whistle being called from above interrupts his thoughts, and Haruka looks up. Makoto's mother Michiko smiles down at him, beckoning him towards the surface, and with a flick of his tail Haruka abandons the poor shredded kelp and joins her at the surface.

“Are you ready, Haruka?” She asks, watching him with glimmering green eyes just a few shades darker than her son.

Haruka nods, throat closing up abruptly. He hopes he doesn't look too shaky. It's not that he's regretting this – he's being bonded to _Makoto_ , how could he ever regret it – but he _is_ nervous. This will make the first day of the rest of their lives together, inseparable. The thought is happy, but heavy.

Michiko seems to notice, and her smile softens as she pats him on the cheek. “I'm glad it's you. There's no one else in the ocean I'd rather see my son swim with, Haruka.”

Haruka feels his cheeks heat up, and he looks down at the water, wanting to dive into it to cool them off but not wanting to be rude to his bondmate's mother, so he nods again. She laughs softly at him, which only intensifies the embarrassment, and he looks to the side and refuses to admit he's pouting.

“Ah, that reminds me, we need to get you adorned,” she says, and Haruka looks up from his not-a-pout in confusion. Adorned? She just smiles mysteriously, clapping her hands, and before Haruka can process what's happening splashes surround him and he's suddenly encircled by several females of Makoto's pod. They're giggling and draping stuff over him before he can protest, and just as suddenly as they arrived they vanish, black fins slipping under the water and leaving Haruka blinking rapidly. What...?

He raises a hand to see that he's been draped in oyster stones interwoven with a blue seaweed to make decorative ropes. A cautious hand to his head reveals a drape of the same sort of thing, and he looks behind himself to see an intricate network of the iridescent white stones and bright blue plant trailing behind him, almost the full length of his body. The seaweed isn't wilted at all – it must have been done recently, but he can't imagine finishing this all in just this morning.

He looks back at Michiko, who giggles softly again at the confusion written on his face. “I may have had a hunch when you arrived this cycle that there would be need for a bonding ceremony, so the girls and I have been working on this since you came.”

Haruka doesn't know what to say – he doesn't think he's worth this sort of work. And this certainly didn't help the red cheeks situation. He looks back down at the water, trying to find something to say. “...This is a lot of oyster stones.”

It kind of is. They're all large and lovely, and there must be at least a hundred in the headdrape alone.

“Only the best for my eldest son's bondmate,” Michiko says, almost proudly. She regards him with a critical eye for a moment, before nodding and smiling, holding out her hands. “You look beautiful. Now, it's almost time for the ceremony. Let's get started and stop Makoto from creating a whirpool with all the circles he's swimming in, shall we?”

His heart jumps into his throat again as Haruka hesitantly takes her proffered hands. This is it.

Michiko smiles reassuringly at him, as if she can sense his nerves, and guides them underwater, holding Haruka's hand as they swim towards the place decided for the ceremony – a secluded inlet with a beautiful arch of rock in the middle. The water is especially clear in this little inlet, and Haruka looks around with wide eyes at the beauty of the simple place. It's not far from the feeding ground, but he's never been here before, usually too busy with Makoto and the twins to explore.

The rest of Makoto's pod has already gathered, and Haruka feels his nerves triple. He likes them, really, but their gazes aren't doing anything to quell his nervousness.

It's the one curse of being with a blacktail – no concept of privacy.

They approached the gathered pod, and Haruka instinctively scans for Makoto, eyes darting restlessly, searching for his about-to-be-bondmate. Where is he?

Then the pod swirls, pulls apart a little, and Haruka's world narrows down because there he is.

He can see the exact moment Makoto spots him, as well – mouth dropping open a little, green eyes widening and filling with something Haruka can only describe as _light_. The rest of the pod suddenly doesn't matter, everything faded and muffled as Haruka lets go of Michiko's hands to swim forward on his own, reaching out to automatically twine his fingers with Makoto's, who swam forward to meet him halfway. He looks into those green green eyes, shining down at him, and there's no nervousness anymore. Not even when Makoto pulls his hands gently and they break the surface, followed by the rest of the pod. It doesn't matter when their voices raise in song – Haruka doesn't recognize it, it's not the song silvertails use for bonding, but it doesn't matter because it's all perfect anyways and he's not the one who has to sing it – as the Elder females start adorning them with ceremonial trinkets, speaking the words of bonding as they tie Haruka's left and Makoto's right hands together with roped kelp as a proper bond. They won't untie it – it will stay until it falls off on its own, as is traditional. The feast afterwards is an equal blur – he eats _something_ , because it's a long swim back home and as one of the honored persons he's stuffed with delicacies, like bottom-dwelling flat fish and delicate seabird, things that he's personally never tried before. They're good, but they're not mackerel.

No, all that matters is those green eyes, and wondering smile, and the dusted red on Makoto's cheeks, and the firm warmth of his fingers locked with Haruka's – they haven't let go since the start, not once. Not that they can, of course, with the kelp binding their wrists, but they don't want to, either.

Finally, as the day starts to wane, the Brightcircle sinking into the end of the sea, it's time. The feast is over, the ceremony is over. There's only one thing left.

Makoto and Haruka say goodbye to Makoto's family in private, huddling in a little group, sharing hugs – as best Haruka and Makoto can, tied together – and humming farewells as they exchange tail rubs, cementing their status as family. The twins cry, of course, clinging to them, and Makoto's parents are misty-eyed, petting their son's hair and giving him low encouraging, loving words. It's not goodbye forever, of course – now Makoto will make the yearly journey with Haruka, to return to this spot and meet his family – but it's still the first time they'll be apart. It makes even Haruka's throat close up, a little. It's odd, because it's not like he's going to see them any less than he usually does, but it still feels like some sort of parting for him, too.

Then, when the twins finally calm down enough to let them go, when all possible words have been said, Makoto and Haruka detach from the little group, giving one final goodbye song to his pod before Haruka squeezes Makoto's hand firmly, and they kick off into a steady swim, Haruka leading the way on the familiar current he's swam for many cycles now.

The blacktails and their past drift into the distance, farewell songs following them, and Mkaoto's hand is steady and warm in Haruka's as they swim back home. To their future together.

 

* * *

 

 

“Ahhh, it's finally spring! Sun! Flowers! Sea! _Mermaids_!!” Nagisa bellows excitedly as they board the research vessel, sprinting up to the bow of the boat with arms flailing, ignoring the startled shouts of the crew. Looks like a new group this round, they'll be traumatized by the blond in short order. 

Rei sighs as he adjusts their bags over his shoulder. Why is he doing all the work again? Why is he bothering asking himself that anyways, he knows the answer. “Please don't run, Nagisa-kun, it's slippery and you might fall.” 

It's a warning he repeats every time they board a boat, and it's a warning that's ignored just like the last million times as Nagisa climbs the front railing, bouncing on his toes. 

“Do you think we'll see Haru-chan today? It's still a little cold, I guess, but he could be sunning himself!” Nagisa's eagerly scanning the shoreline, as if his sheer enthusiasm could magically summon the merman to his sights. Rei reaches out and hooks his hand into the hood of Nagisa's jacket, gently but firmly pulling him off the rail as the boat's engine starts with a shudder and they start sailing through the water. Nagisa gives him a pout that Rei easily ignores. “It is not outside of the realm of possibility, to see him today, but there is an equal chance of not seeing him. It is up to luck.” 

“Oh Rei-chan, always so logical and ruining my fun,” Nagisa grumbles, sticking his lips out as he exaggerates his pout, before turning to rummage through the bag still hanging off Rei and pulling out the binoculars, propping his elbows on the railing and humming as he scans the distant rocks for any sign of their subject. 

Knowing that their destination is still at least half an hour away, Rei pulls out his notebooks and starts the routine documentation for the beginning of the season. Wind speeds, water and air temperatures, dates, times, lunar cycles, he records it all down neatly as the boat chugs along. 

After it sails a fair distance through the bay, leaving behind the populated fishing area and approaching the secluded parts where Haru likes to swim, it drops anchor, stopping with a shudder, and soon the world is engulfed in calm – no sounds but birds, sea wind, and ocean waves slapping the sides of the boat. 

It's all very relaxing, and Rei soon gets into a zone, filling out sheets of his notebook with ideas and calculations. He's in the middle of writing a complicated one correlating _syreni_ tail hue to water mineral content when Nagisa makes an excited squeal, jumping up and down. “Rei-chan, Rei-chan!” 

There it goes, the formula is gone now, and Rei grimaces at his paper before sighing. He's not getting it back now. Snapping the notebook shut, Rei looks up, adjusting his glasses in a pointedly-annoyed move. “ _What_ , Nagisa-kun?” 

Nagisa blithely ignores his irritation with long practice, patting his arm excitedly and pointing. “Look, look! It's Haru-chan!” 

Rei glances up in surprise – indeed, their lone _syreni_ subject is on his “favorite” rocks, appearing fast asleep. Rei's irritation instantly fades and he smiles. While he believes in being realistic and not getting your hopes up, it's still nice to see the good outcome being the correct one. 

Nagisa's bouncing on his feet again. “Look at him, all sleepy! Haru-chan never changes! It's nice to see him again, I wonder if we'll learn anything from him this year too?” 

“Of course we will. Everything we record is new knowledge,” Rei states, a little haughtily – he is proud to be on the cutting edge of science, of course! – but with a genuine smile. Really, he's excited too. What wonders will Haru show them this year, he ponders. 

His answer comes a little sooner than expected, because as Rei's watching, the black shape behind Haru that he'd assumed to be part of the rock formation Haru is resting on _moves_. 

It shifts, swirls, revealing white patches swirled through it, and suddenly there's a torso, tan and strongly-muscled, stretching in a yawn. Rei can barely breathe. 

It's another _syreni_. 

Nagisa makes a strangled noise next to him, pink eyes wide and shining. Rei's mind automatically begins calculating the new anomaly, recording its data in the same form he'll write down later to record the specimen, but he's too shocked to write right now. 

Male. Large, larger than Haru, by probably quite a few centimeters. Brown shaggy hair and a handsome face, from what Rei can tell from this distance. 

And the _tail_. It's the tail that really makes Rei gasp in wonder, because that's not a dolphin-morph tail at all. 

Well, technically it is, he supposes, since orcas are a part of the dolphin family. 

It's an orca morph. They're rare to see this close to land, and hard to study, and one is right there. An orca morph, nowhere near any other orca morphs – they're never apart! What's going on? – right there on the rocks with their subject...not just with, _on top of_ , as the newcomer shifts to lie down again, sprawling over Haru's back and nuzzling into it, looking perfectly content to settle back down into sleep. 

And Haru, standoff-ish Haru who deliberately swims away from his pod, doesn't move. There's a languid tail-flop as the larger syreni settles on top of him, but Haru doesn't react any other way at all, content to keep sleeping with the newcomer using him as a pillow. It's completely different behavior form what they're observed from Haru in the past – once Rei even recorded him actively _chasing away_ receptive females! – and Rei is mystified. It's magical. Haru is giving them new data right now and they have a new subject and it's a breathtaking moment. 

Nagisa shatters it. 

“Oh my _god_ , he's got a mate! Haru-chan found a mate! He's all grown up now, I'm so proud of him!!” Nagisa all but _shrieks_ , jumping up and down, hands clasped to his chin in a picture of teenage girlish glee if it weren't a twenty-five-year old completely certified scientist _this is a grown adult_ doing it. 

Rei is struck with an immense urge to smash his forehead into the rail at high velocity. 

His peace is not the only one Nagisa breaks, as the newcomer syreni hears it too – and reacts less favorably. The large male bolts upright, eyes shooting open. There's a brief second of panicked looking around, before he spots the boat – and immediately surges off the rock, belly-flopping into the water in a distinctly ungraceful panicked exit. 

Well, there goes any new data for the day. 

“Awww!” Nagisa pouts for the second time that day, heaving a sigh. “I didn't mean to scare him off! I was just excited...” 

“Well, mean to or not, you did it anyways,” Rei points out, not feeling really helpful at the moment. “And Haru doesn't look very happy about it either.” 

Indeed, the sleek dolphin morph has also woken up and propped himself on his elbows, giving their boat a very dirty looks before sliding off the rocks and into the water, leaving barely a ripple – much contrasted to his acquaintance's ungainly splash, complete with flailing limbs. Nagisa gives an exaggerated sigh, flopping over the railing and draping on it in the very picture of desolation. “I didn't mean to! Come back, Haru-chan, Haru-chan's mate! I just want to get to know you!” 

Rei sighs, because that means no more study for today – he doubts the _syreni_ will let them approach, now. They'll have to try again later.

Still, Rei is actually not all that irritated. Yes, he's rather put off by their study being cut short today, but what they found today more than makes up for it. 

There's an orca morph in their bay. One that, for all intents and purposes, Haru seems very close to – indeed, perhaps even mated, as Nagisa blurted out. Same-sex pairings are not uncommon in _syreni_ , they've found. If it's true, and if they can avoid scaring him off again, they'll be one of the first people in the world to document mated _syreni_ behavior. Homosexual, at that. 

Rei gives a little smile to himself. This summer will be a good one.

 

**Notes for the Chapter:**

> The bonding ceremony ended up being trash literally could not write anything better sorry #aroproblems
> 
> -rolls around in rubbish-

**Author's Note:**

> As always, for more recent updates - and if you'd like to listen to me screech about fandoms too - you can check me out on tumblr - clover-magic.tumblr.com


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